Well, Bobby, when I pull out onto IN-46 and make the right to take the kids to school in the van, it's embarrassing. It seems to be making all the right noises and stuff, but it moves like it's tied to a post. My old Chevy is quick--I can pull pretty much right out in front of people. Before I put the No-Spin in it, it would burn the tire and I would have to let off and wait for grip. The van is embarrassingly slow. You floor it, it gives a bit of a push and some promising turbo whistle, but it never really gains speed. On the interstate, with the cruise set, it has good power. When the cruise is off, you can't keep up using the pedal. I noticed this on a 2003 F350 as well. I think a flash of the chip might give the driver some fuel, but it's pathetic right now and I only like to drive on trips.
I would be happy for someone to drive my 6.2 and post their feelings. You aren't going to be disappointed. I've borrowed a 2003 7.3 6-speed F350 4x4 dually on 2 long trips, and my 6.2 truck is stronger. The guy I borrowed the F350 from drove my truck when I had his and said he was impressed. I think he said "You press the pedal and it just goes." I think it's a reference to the fact that Ford doesn't give you any fuel unless the cruise is set. I found his truck absolutely pathetic until I set the cruise. In the hills in Pennsylvania, I was downshifting and downshifting and all I was pulling was a 2,500# '65 Mustang on a 1,300# utility trailer. Once I hit the cruise, it was a miracle. Our van is like that. But it doesn't help you when you need to accelerate with your foot.
There are so many 6.2/6.5s out there, though, that I can't endorse them. My truck has the, I think, 480 block in it. My previous truck was newer and had a Goodwrench 5-something block. I kept that motor because I heard it wouldn't crack. I expected my motor to fail and to have to install that one. I have another 480 (I think) motor with low miles from an Air Force truck. And I have that transmission as well. I have 2 back-up motors because I thought mine would fail. That's not an endorsement. But it hasn't failed.
I'll accept people's personal stories, but not a generalization. This is a motor that has been built since 1981 and is still in production. I was 12 in 1981. Why is it still around? There is lots of other military gear that came into being after that and disappeared before it, but the allegedly bad 6.2/6.5 chugs on. Chugs on. Chugs on.
For instance, in the marines, my primary weapon was the
M198 howitzer. The Marine Corps didn't replace their M114s until after 1987. Now, as 0f 2008, they have the British built
M777 The 6.2 was leading the M198s into position when they first came out, and right now, it's leading the M777s. As far as I know, there's no replacement in mind. That means, if you buy a 30 year-old 6.2 and set your truck up for it--you will be able to install a new 6.5 into it exactly in it's place.
The HMMWV (or whatever it's called) has got to be the most common heavy-duty light truck ever built. And your plan is to discount it's powertrain as an option for your own truck?